The Al₂O₃ supported Ni-P core-shell structure nanoparticles has been prepared by electroless nickel plating with Pd-free surface activation method in this investigation. The Al₂O₃ nanoparticles as a support with diameter about 20-45nm were surface modified with alkaline solution and followed by adsorption of nickel ions at room temperature. Nickel clusters served as catalytic sites for electroless Ni-P plating were obtained by hydrogen gas reduction at 500℃ for 2 hours. The Ni-P layers were successfully deposited on the surface of Al₂O₃ nanoparticles by electroless nickel plating. Characterization of the Ni-P(shell)/Al₂O₃(core) structure was studied by transmission electron microscopy (TEM), field-emission scanning electron microscopy (FE-SEM) and electron spectroscopy for chemical analysis (ESCA). Core-shell structure was clearly observed by TEM. Surface morphology of alumina nanoparticles with nickel adsorption was examined by FE-SEM. Distribution of nickel and phosphorus on alumina was identified by ESCA.

Carbon onions consist of closed fullerene-like shells enclosed within one another or multishell fullerenes. We will give short overview of various approaches for carbon onion synthesis, their properties and the most recent applications [1].

Our group has developed method of functionalsisation of carbon onions [2]. The functionalization of onion-like carbon (OLC) nanoparticles with anthracene by direct covalent bonding is confirmed by XPS and Mid-IR and UV spectroscopy [2]. The new chemical route is based in the bromine/lithium exchange, commonly used for aliphatic compounds, applied here to aromatic carbon. Our results provide a new procedure for the chemical functionalization of the OLC nanoparticles, which could be also a new route to functionalization of other families of carbon nanoparticles.

In addition we studied the potassium intercalation of onion-like carbon (OLC) samples consisting of aggregates of carbon onions by photoemission spectroscopy. OLC samples were initially prepared by annealing nanodiamonds (3-20 nm in diameter) at 1800 K in vacuum [3]. The resulting OLC consists of closed fullerene-like shells. The ‘closed’ OLC was subsequently treated with carbon dioxide at 1020 K in order to open the carbon shells by partial oxidation to create ‘opened’ OLC. Core-level and valence-band photoelectron spectroscopy have both been employed in characterizing the changes in electronic structure of the samples [3]. Upon intercalation of the closed OLC with K the C1s core-level and valence band features shift to higher binding energies and the density of states at the Fermi level increases, while this effect is significantly smaller for intercalated opened OLC. These results indicate that opening the shells of carbon onions allows potassium to penetrate inside the particles and thus opens up a possible route to fill carbon onions with desired substances and their application as nanocapsules [3].

[1] “Carbon Onions ”, Y. V. Butenko, L. Šiller and M.R.C. Hunt in Handbook of Nanophysics, CRC Press LLC, in press.

[2] A.C. Brieva, C. Jeger, F. Huisken, L. Siller, Y.V. Butenko, Carbon, 47, 2912 (2009)

[3] Y.V. Butenko, A.K. Chakraborty, N. Peltekis, S. Krishnamurthy, V.R. Dhanak, M.R.C. Hunt and L. Siller, Carbon, 46, 1133 (2008)

The authors provide the formation and memory effects of W nanocrystals nonvolatile memory in this study. The charge trapping layer of stacked a-Si and WSi₂ was deposited by low pressure chemical vapor deposition (LPCVD) and was oxidize d by in-situ steam generation system to form uniform W nanocrystals embedded in SiO₂. Transmission electron microscopy analyses revealed the microstructure in the thin film and X-ray photon-emission spectra indicated the variation of chemical composition under different oxidizing conditions. Electrical measurement analyses showed the different charge storage effects because the different oxidizing conditions influence composition of trapping layer and surrounding oxide quality. Moreover, the data retention and endurance characteristics of the formed W nanocrystals memory devices were compared and studied. The results show the reliability of the structure with 2% hydrogen and 98% oxygen at 950℃ oxidizing condition has the best performance among the samples.

In this work, we propose a novel method to fabricate nickel nanocrystals structure by co-evaporatin Ni and SiO₂ pallets, simultaneously. A high density nanocrystals distribution about 4.5×10¹² cm^-2 was found after a 800℃ rapidly thermal annealing process. Moreover, the co-evaporated method to form Ni nanocrystals reveals multi- and single-layer structure after 700 and 800℃ annealing process, respectively. The detailed formation mechanisms for the different nickel nanocrystals structure of each temperature have been discussed. It is believed that the distributed nucleation sites of the co-evaporated film play an important role in the nanocrystals formation. In addition, we also compared with the memory devices by using the formed nickel nanocrystals structures as the charge trapping layer. The nickel nanocrystals memory devices show an obvious memory and good reliability characteristics in the electrical measurements. The results also confirm that the co-evaporated method to form the nanocrystals structure is easy and potential to apply into the current memory device.

One of the popular synthesis methods for making graphene oxide (GO) is based on the Hummer process. However, little or no information is available regarding the details of the fabrication of GO. We have assessed in this study some critical steps and parameters during the synthesis of GO based on the Hummer process. They include the rates at which the relevant chemicals and solvents are added into the processing bath, the compositions and concentrations of the processing bath, and the bath temperature. The resulting GO were dispersed in either water or Tetrahydrofuran. The suspension fluids, having various GO concentrations, were then spun on to polyethylene terephthalate substrates. The obtained transparent, conducting samples are then subjected to flexibility tests and characterized for the optical and electrical properties. The characterizations were performed before and after the flexibility tests. Correlation between the GO processing steps and parameters to the characteristics of the transparent, conducting films are reported.